The background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.
These and all other extrinsic materials discussed herein are incorporated by reference in their entirety. Where a definition or use of a term in an incorporated reference is inconsistent or contrary to the definition of that term provided herein, the definition of that term provided herein applies and the definition of that term in the reference does not apply.
Optical fiber splicing is used to join ends of two optical fibers in a firm connection in order to couple optical power from one optical fiber to other optical with minimum or no power loss. One approach for joining two optical fiber ends is mechanical splicing. A mechanical splice is used to join two optical fiber ends by abutting the ends fixed within a structure. Although mechanical splicing joins two optical fiber ends, it is difficult to achieve splicing with low signal light loss due to several factors. For example, some of the factors that produce losses in mechanical splicing are lateral displacement of abutting fiber cores, misalignment of fiber axes (i.e., angular misalignment of the fiber ends), differences in the numerical aperture between the fibers, fiber glass cracking and/or debris between the fiber ends, reflections at fiber ends, surface finishes on the fiber ends, and mechanical and environmental stresses induced factors mentioned previously on the optical fiber itself.
The design of the structure containing the mechanical splice (e.g., a barrel assembly or other housing structure) is critical in preventing losses. Both fibers should be assembled along a precise center line with minimum deviation or separation in order to assure minimum optical insertion loss during splicing. A poorly designed structure will result in bad optical splicing installation and product field operation performance against mechanical and environmental stresses.
Most field terminable connectors rely on a very precise V or U groove to guide two fiber ends to abut one another, and the fiber ends are fixed in position with the help of a press plate. Due to the manufacturing tolerances and distortion caused by press plate actuation forces, these types of splicing members are difficult to create a precise enough aperture for optical fiber splicing that is positioned along a precise center line. Consequently, splicing performance suffers and micro or macro bending is introduced in the system after an optical fiber and a fiber stub are locked in place. Typically, many components are needed in this type of splicing mechanism which further increases the risk of insertion losses due to (i) splicing components being over constrained and offset from component center line, and (ii) micro or macro bending induced. Furthermore, many field terminable connectors require an installation platform to ensure that the optical fiber is abutting the fiber stub before both are locked in place. Consequently, extra equipment may be needed at various job sites if an installation platform is required.
Various optical fiber connectors have been contemplated without installation platform. For example, Park (U.S. Pat. No. 8,840,320) describes an optical fiber connector having a splicing element. The connector comprises a ferrule having an optical fiber stub that is spliced with a bare fiber from a field optical fiber cable. The two fiber ends abut one another within the splicing element, and are locked in place by attaching a cap to the splicing element. The locked splicing element floats within a backbone having a clamping portion to clamp the field optical fiber cable. During installation, the field optical fiber is inserted into the backbone until a coated portion of the field optical fiber cable begins to bow/bend, and the field optical cable is locked to the backbone prior to the cap being applied to lock the splicing element. It is necessary for this design to form cable bowing/bending in order to provide mechanical compliance during connector mating/un-mating to mitigate the undesired losses. Consequently, the movement of cable bowing during numerous mating/un-mating actions will affect splice element reliability.
Various optical fiber connectors have been contemplated without V or U groove in splicing element. Wang (U.S. Pat. No. 7,883,275) describes a fiber optics connector having a 3-rod bundle used to splice a fiber stub and an optical fiber of a field fiber optic cable. The 3-rod bundle is assembled in accordance with Soddy Circle geometry to create an aperture that receives the fiber stub and the bare fiber. Other 3-rod bundles for mechanical splicing have been described by Tardy (U.S. Pat. No. 3,989,567) and Kao (U.S. Pat. No. 4,047,796). However, due to the difficulty to pack a 3-rod bundle, such rods can deform when brought together to create a 3-rod bundle. Additionally, manufacturing the rods of a harder material can be expensive and economically undesirable for production of 3-rod bundles.
Thus, there is still a need in the art for improved field installable optical fiber mechanical splicing connectors with minimum installation tool while providing a robust performance design.